1. Field of the Invention
The invention relates to a directional coupler in coaxial line technology.
2. Description of the Related Art
Directional couplers are used in high frequency technology for separate measurement of a go-and-return wave in a line. In the end stages of amplifiers, directional couplers are used for example to measure the voltage standing wave ratio. A directional coupler is hereby used selectively in coaxial line technology.
A directional coupler of this type in coaxial line technology is described for example in U.S. Pat. No. 5,926,076. The directional coupler hereby comprises a coaxial line with an inner conductor, a hollow-cylindrical dielectric guided around the inner conductor and a hollow-cylindrical outer conductor which is applied on the casing of the hollow-cylindrical dielectric and a printed circuit board on which the two decoupling units of the directional coupler are essentially applied. Coaxial line and printed circuit board with decoupling units are disposed at an adjustable spacing relative to each other in a housing.
The comparatively high complexity with respect to a mechanical and also electrical connection between the coaxial line and the two decoupling units and the connections thereof via a common spacing, attachment and mounting in a common housing is disadvantageous in this arrangement. Also the specific and efficient discharge of heat produced from the directional coupler circuit by means of resistors and heat discharge bars has a comparatively complex configuration.